Tian Jin Dian Zi Biao

This is a rare clone of the Accutron 214 that was made in China.
I restored this one to running condition.

More photos inside!

This Tian Jin was sent to me for repairs. I
found all coils open and the electronics dead, as well as various mechanical
problems including a broken stem and jewel.

After restoration, it runs and regulates and sounds just like a 214, at the
same frequency. Final rate when flat is -1.6; tines down +2.5; tines up -6.5

Bad Electronics

After consultation with the owner, I left the
original dead circuitry components for appearance's sake, and built a new
driver circuit in between the solder pads under the dial. That space is 0.8mm
tall, so I used 0.5mm tall surface mount components. This excludes the popular
SOT23 transistors which are too tall, so I had to use a very tiny package. Then
I rewound both coils to match. Final unloaded current is about 2.5uA, running
the train is 5uA. Amplitude is about 1.5 teeth on silver oxide. This approach
leaves us with a totally reversible repair that gives us a reliable running
watch, and the appearance is all original when assembled.

Open Coils

Here's the circuit side coil, rewound but not
yet soldered or coated for protection. The coil forms seem to be made of the
same plastic exactly as the 214, but the castings are much lower quality. The
bobbins that hold the wire are larger, so when wound with the 214's parameters
they were not very full. I wound extra wire to give lower amplitude in case the
index wheel was worn.

The original index wheel is good, or at least good enough!

Broken Stem

I fixed the original stem, which was in good
condition except the thread being broken off, by drilling and tapping it and
inserting a new threaded portion with thread (tap size) that matches the
original (0.8mm). There was just enough of the old thread left to measure. I
installed a new waterproof crown. Interestingly the case has an internal
O-ring that seals against the smooth part of the stem. With a traditional
waterproof crown, this gives a double seal. It came to me with a tension ring
crystal, and I installed a new O-ring on the case back. This is a much more
waterproof watch than the 214.